Characteristics of gully bed scour and siltation between check dams

Check dams are the most commonly used engineering measure for debris flow control worldwide. The scour and siltation characteristics between dams are important factors affecting dam design. In this study, classical dimensional analysis of the variables that influence the development of gully bed scour and siltation was carried out. Flume experiments were conducted to examine the influence characteristics of opening width, flume slope, debris flow density, and opening rate on the characteristics of gully bed scour and siltation. The influential characteristics of variables on the dimensionless scour depth, scour length, siltation length, scour volume and siltation volume were obtained. The experiments showed that, with an increase in the relative opening from 1.5 to 2.5, scour depth increased by 7.4%, scour length decreased by 11.2%, siltation length increased by 22.0%, scour volume decreased by 4.7% and siltation volume increased by 22.0%. With an increase in flume gradient from 0.105 to 0.213, scour depth, siltation length and siltation volume increased by 40.0%, 65.9% and 65.9%, respectively, and scour length decreased by 20.1%. With an increase in sediment concentration from 0.303 to 0.545, siltation length and siltation volume increased by 15.4% and 15.4%, respectively, and scour depth, scour length and scour volume decreased by 9.6%, 9.1% and 17.8%, respectively. As opening rate increased from 0.08 to 0.32, siltation length and siltation volume increased by 33.3% and 33.3%, respectively, and scour depth, scour length and scour volume decreased by 5.4%, 13.7% and 18.4%, respectively. The results showed that the flume gradient was the most influential factor on scour depth, scour length, siltation length and siltation volume, and the sediment concentration was the most influential factor on scour volume. Then, according to the experimental data, some empirical formulas predicting scour depth, scour length, siltation length, scour volume and siltation volume were obtained. The error between the computed values according to the formulas in this paper and the observed values was within +/- 10%. These research results may provide a technological basis for window dam design in debris flow disaster prevention and mitigation.

Automated summary

This study investigated the influence characteristics of opening width, flume slope, debris flow density, and opening rate on the characteristics of gully bed scour and siltation. The results showed that flume slope was the most influential factor on scour depth, scour length, siltation length, and siltation volume, while sediment concentration was the most influential factor on scour volume.